I tackled the mechanical part first by figuring out the various movement profiles. Each move the house made required careful discussion and engineering. Rotating the entire house could be done in several ways. The first and most obvious idea was to build a turntable underneath the house, but a turntable would have added significant load-in time and required installing an expensive surround deck.
So we decided to support the house on its own wheels. The next question was: How do we drive it? We already knew that the motor’s speed and position would be controlled by our automation system (Spikemark software and Stagehand controller from Creative Conners). The spiral stairs seemed like a possible drive point; they were at the center of the house and circular. Could we use that as a gear to drive the upper unit? Given the modest 5-foot diameter of the spiral staircase, quick calculations suggested that the power required would exceed 12 horsepower, and would create reaction forces greater than I cared to resolve.
So we decided to make the house turn itself. We hung motors under the first floor of the house, and used tires to push the house in a circle.
To say making a self-driving house is not an easy task is an understatement. Think about a car: The four wheels of a car support the load of the vehicle while maintaining contact with the ground. However, you’ll also notice that when you get into a car with several of your friends, the car lowers closer to the ground as it gets loaded. Cars have suspensions to compensate for road variations, rider comfort, and load balancing. But a three-story house on a suspension would wiggle, shift, and settle as actors moved around it. We decided to use a rigid frame to stabilize the house.
But what could the motor and wheels run on? Obviously we couldn’t just let a three-story house on wheels run on the bare fiberboard floor and expect the stage to stay intact. That took some trial and error. We tried using a spray-on truck bed lining bonded to a metal plate, but that peeled off in one rotation. We settled on a circle of perforated sheet metal, which created enough traction so the wheels wouldn’t slip and would also protect our stage.